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The role of reproductive factors and use of oral contraceptives in the aetiology of breast cancer in women aged 50 to 74 years.
Int J Cancer 1999; 80(2):231-6IJ

Abstract

It is unclear whether age at menarche is causally involved in breast-cancer aetiology, or serves a correlate of other early-life exposures. Other aspects of reproductive life, including cycle length and regularity, climacteric symptoms, reproductive history and oral contraceptive use, are also incompletely investigated. We examined these issues in a population-based case-control study, including 3,016 women aged 50 to 74 years with invasive breast cancer, and 3,263 controls of similar age. Mailed questionnaires and telephone interviews were used to collect information on menstrual and reproductive characteristics as well as use of oral contraceptives. We found a statistically significant negative association between increasing age at menarche and breast-cancer risk in women born before 1925 but not after. Length of the menstrual cycle at age 30 seemed to be adversely related to breast-cancer risk, with OR for women with cycle lengths < 24 days and > 30 days being 0.76 and 1.18, as compared with women with a cycle length of 28 days. There was a strong trend of decreasing breast-cancer risk with increasing parity (OR per borne child 0.85, 95% CI 0.80-0.90). Lactation, menopausal symptoms or past use of oral contraceptives did not appear associated with breast-cancer risk. Our findings provide some evidence of a role of environmental correlates of early menarche in breast-cancer aetiology, and underline the importance of childbirth, especially early in life, in the prevention of breast cancer. Our data are not readily compatible with an important influence of former oral contraceptive use on post-menopausal breast-cancer risk.

Authors+Show Affiliations

Department of Medical Epidemiology, Karolinska Institute, Stockholm, Sweden. Cecilia.Magnusson@mep.ki.seNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9935204

Citation

Magnusson, C M., et al. "The Role of Reproductive Factors and Use of Oral Contraceptives in the Aetiology of Breast Cancer in Women Aged 50 to 74 Years." International Journal of Cancer, vol. 80, no. 2, 1999, pp. 231-6.
Magnusson CM, Persson IR, Baron JA, et al. The role of reproductive factors and use of oral contraceptives in the aetiology of breast cancer in women aged 50 to 74 years. Int J Cancer. 1999;80(2):231-6.
Magnusson, C. M., Persson, I. R., Baron, J. A., Ekbom, A., Bergström, R., & Adami, H. O. (1999). The role of reproductive factors and use of oral contraceptives in the aetiology of breast cancer in women aged 50 to 74 years. International Journal of Cancer, 80(2), pp. 231-6.
Magnusson CM, et al. The Role of Reproductive Factors and Use of Oral Contraceptives in the Aetiology of Breast Cancer in Women Aged 50 to 74 Years. Int J Cancer. 1999 Jan 18;80(2):231-6. PubMed PMID: 9935204.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The role of reproductive factors and use of oral contraceptives in the aetiology of breast cancer in women aged 50 to 74 years. AU - Magnusson,C M, AU - Persson,I R, AU - Baron,J A, AU - Ekbom,A, AU - Bergström,R, AU - Adami,H O, PY - 1999/2/6/pubmed PY - 2000/6/20/medline PY - 1999/2/6/entrez KW - Biology KW - Breast Cancer--etiology KW - Cancer KW - Case Control Studies KW - Contraception KW - Contraceptive Methods KW - Developed Countries KW - Diseases KW - Epidemiology KW - Europe KW - Family Planning KW - Health KW - Neoplasms KW - Northern Europe KW - Oral Contraceptives KW - Public Health KW - Research Methodology KW - Research Report KW - Risk Factors--women KW - Scandinavia KW - Studies KW - Sweden KW - Women SP - 231 EP - 6 JF - International journal of cancer JO - Int. J. Cancer VL - 80 IS - 2 N2 - It is unclear whether age at menarche is causally involved in breast-cancer aetiology, or serves a correlate of other early-life exposures. Other aspects of reproductive life, including cycle length and regularity, climacteric symptoms, reproductive history and oral contraceptive use, are also incompletely investigated. We examined these issues in a population-based case-control study, including 3,016 women aged 50 to 74 years with invasive breast cancer, and 3,263 controls of similar age. Mailed questionnaires and telephone interviews were used to collect information on menstrual and reproductive characteristics as well as use of oral contraceptives. We found a statistically significant negative association between increasing age at menarche and breast-cancer risk in women born before 1925 but not after. Length of the menstrual cycle at age 30 seemed to be adversely related to breast-cancer risk, with OR for women with cycle lengths < 24 days and > 30 days being 0.76 and 1.18, as compared with women with a cycle length of 28 days. There was a strong trend of decreasing breast-cancer risk with increasing parity (OR per borne child 0.85, 95% CI 0.80-0.90). Lactation, menopausal symptoms or past use of oral contraceptives did not appear associated with breast-cancer risk. Our findings provide some evidence of a role of environmental correlates of early menarche in breast-cancer aetiology, and underline the importance of childbirth, especially early in life, in the prevention of breast cancer. Our data are not readily compatible with an important influence of former oral contraceptive use on post-menopausal breast-cancer risk. SN - 0020-7136 UR - https://www.unboundmedicine.com/medline/citation/9935204/The_role_of_reproductive_factors_and_use_of_oral_contraceptives_in_the_aetiology_of_breast_cancer_in_women_aged_50_to_74_years_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&amp;sid=nlm:pubmed&amp;issn=0020-7136&amp;date=1999&amp;volume=80&amp;issue=2&amp;spage=231 DB - PRIME DP - Unbound Medicine ER -